Dosing devices for dosing treatment compositions in a dish or laundry washing machine are representative of the various dosing devices to which the present invention can apply. Typically, such dosing devices comprise at least one compartment which is filled with product by the consumer, and at least one opening which is such that said product is mixed with wash water during a wash cycle. Such dosing devices are interesting because the compartment is usually designed such that it contains substantially the amount of product necessary for one wash cycle. So the dosing device allows for dosing and direct release of the product onto the items to be treated. Such dosing devices are usually re-usable.
A lot of improvements have been brought to dosing devices through the years, all directed to a better dosing and/or release the product during the wash. Especially, it was seen as an important feature that the release of the product may be delayed, for example till the last phase of the wash cycle.
Some dosing devices comprise more than one compartment. Typically this type of devices are used for products that are incompatible, but which must be added in the same wash water, for example in EP.0.236136 A1 to Unilever.
Some other devices comprise a means for releasing their contents progressively during the wash cycle, or even at some point in time during the wash, for example at the spin drying phase or during the last rinse. In case the release needs to be progressive, the device comprises for example vents shaped as restricted openings, for example in U.S. Pat. No. 4,703,872 to Procter and Gamble. In case the release needs to be delayed in the wash cycle, the device comprises mechanical means, for example it uses temperature of the wash water, and the difference of retraction properties of its constitutive materials: for example U.S. Pat. No. 5,768,918 discloses a device comprising a main compartment and a cover to releasably close said compartment, both made out of two different materials. Before the wash, the user fills the device and closes the compartment with the cover. During the wash, at the time the temperature of the wash water changes, typically during the last rinse, the retraction of the cover is more important than the retraction of the compartment's material, such that said cover slides open from said compartment, thereby releasing the contents. Another means used for release product at one point in time during the wash is the use of the centrifugal force at the time of the spin drying. Devices using a compartment releasably closed with a cover that is closed by the user before the wash and then opened by the centrifugal force is for example disclosed in U.S. Pat. No. 3,888,391 to Procter and Gamble.
Other embodiments were found to improve the release of the product at one point in time during the wash, for example the use of porous membranes, for example as disclosed in EP.0.236136 A1.
The dosing devices which can be found in the art solve some issues. However, it appears that in some cases, the conditions in the wash water change from one wash cycle to another, when using the same washing machine. Such conditions depend on the amount of items to be washed, the nature and amount of product that is used, the water hardness, and other parameters. So one main disadvantage is that the opening of the dosing device and release of the product cannot be pre-determined, but depends only on wash water characteristics, which are likely to vary from one wash cycle to another.
It is therefore one main object of the present invention to provide the user with a dosing device which is portable and self contained, so that it can be used for in-house applications, which comprises a means to release the device's contents at a predetermined moment of the wash cycle. In addition, it is an object of the present invention to provide a device that allows to release products that could not be released by a washing machine.